I am trying to be nice, but its getting difficult. 
fuel octane
- Thread starter Vman
- Start date
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ok, ok!! i believe youbwalker said:I am trying to be nice, but its getting difficult.
i am just trying to figure out why higher octane makes a 2-stroke run cooler, that is, according to my stihl manuals....or that is not true?
ccicora
Addicted to ArboristSite
Ben look in the mirror and slap your self.... If you start being a nice guy we'll half to sit down and have a drink sometime.
That would be correct.
I would rather drink my own piss than have a drink with you, Chris.
Simonizer
Addicted to ArboristSite
The octane rating of gasoline is actually a comparison of auto-ignition against a standard. The standard is a mixture of iso-octane (IUPAC name 2,2,4-trimethylpentane) and heptane. A gasoline with an octane rating of 94 for example, exhibits the identical detonation characteristics as a mixture of 94% iso-octane and 6% heptane. Incidentally, as for specific energy, all gasolines are in the 19000-22000 btu/lb range. (Same as parafin wax, diesel and kerosene. Cheers.
Thats what I said.
Simonizer
Addicted to ArboristSite
I know. Take it easy.bwalker said:
Simonizer
Addicted to ArboristSite
I know. Take it easy.12guns said:Ya'll are like a bunch of old women!!!
Diesel JD
ArboristSite Guru
Higher octane is good when called for as with Husky and Stihl, but other 2-stroke equiptment such as water cooled two stroke outboards call for 87 octane. Cars? We have 4 gas cars in the fleet,, my brothers trooper, my dad's Isuzu pick up and my mom's 4Runner all get 87 Octane, but my brothers Mitsu 3000GT calls for premium whih is what he feeds it...go with the manual, and you can't go wrong. Back on topic...with a chiansaw....the cost of fuel is so small that even at todays prices, even if you ran premium it woul be a very small addtional burden.
MotoBoyMatt
ArboristSite Member
Ben, after further research I'll concede that higher octane fuel can have a higher or lower heating value than standard grade depending on differences in formulation, season, presence of ethanol, etc. So they're all in the same ball park as far as heating value.
Vman, I think the point that Ben is trying to get across (and the husky manual for that matter) is that high octane fuel allows an engine to run during hotter conditons without experiencing detonation, pre-iginition and thier damaging effects.
Also, high performance engines have higher compression ratios, the higher the compression ratio the more power the engine can extract from the fuel, this is why diesel powered vehicles get better fuel mileage. The trade off of higher compression ratios is greater risk of pre-ignition and detonation. This is why high performance engines need high octane gasoline. Diesel engines don't have to worry about preignition because the fuel doesn't enter the cylinder until the precise moment that ignition is suppose to occur. They are not, however, imune to detonation and this one of the reasons why diesel engines weigh so much more than their gasoline counterparts.
An increase in power in a modern computer controlled vehicle may be noticed when switching to high octane. This is because the computer may have been sensing pre-ignition with the lower octane fuel and retarted the ignition timing (which lowers power output) to eliminate the pre-ignition.
Vman, I think the point that Ben is trying to get across (and the husky manual for that matter) is that high octane fuel allows an engine to run during hotter conditons without experiencing detonation, pre-iginition and thier damaging effects.
Also, high performance engines have higher compression ratios, the higher the compression ratio the more power the engine can extract from the fuel, this is why diesel powered vehicles get better fuel mileage. The trade off of higher compression ratios is greater risk of pre-ignition and detonation. This is why high performance engines need high octane gasoline. Diesel engines don't have to worry about preignition because the fuel doesn't enter the cylinder until the precise moment that ignition is suppose to occur. They are not, however, imune to detonation and this one of the reasons why diesel engines weigh so much more than their gasoline counterparts.
An increase in power in a modern computer controlled vehicle may be noticed when switching to high octane. This is because the computer may have been sensing pre-ignition with the lower octane fuel and retarted the ignition timing (which lowers power output) to eliminate the pre-ignition.
Chris J.
Addicted to ArboristSite
Simonizer said:
Or anyway that you can get it. Ha, ha, sorry, a throwback to my misspent youth. I had a friend that could've wrote a book on smartazz comebacks.
Ben, the Shell refinery in Deer Park has a Shell retail station just before the entrance to the refinery. Your post makes me curious as to just which gas it sells.
Take it nevermind...Chris J.
Lakeside53
Stihl Wrenching
Out here in WA (Seattle area), from the 1st November, we switch to "winter fuel". For Arco that means 10% ethanol.... I see a lot of saws messed up with old gas AND poor quality gas. Saws run hard on Arco show overheated mufflers and often melting on the plastic over the muffler. We recommend to everyone that they use Chevron mid-grade or above. Chevron says they don't use alcohol in their winter gas.
BTW, just got back from Montana. Regular grade out there is 85.5, and mid-grade is 88.5. Anyone have any insight on this?
BTW, just got back from Montana. Regular grade out there is 85.5, and mid-grade is 88.5. Anyone have any insight on this?
bvaught
ArboristSite Operative
Lakeside53 said:
My guess is that they are at altitude so normally aspirated engines dont need as high an octane.
May be slightly off topic, but I recall having peeked into this a few years back, as there is a tank farm right around the corner from me.
To my shock--nowadays (as opposed to 15 years ago) all gas is the supposedly the same, as to the gasoline part that is. The difference between brands (exxon, bp-amoco, etc.) and octanes, which differences are not insignificant, is in the "patented" additives, detergents, etc., of each "producer." The only things that the producers produce are their buckets of additives. The "slugs" of gas from various refineries arrive at the tank farms in the transcontinental pipelines, 30 to 36 inch, where the gas is then stored in the dealer tanks, where their "unique" additives are mixed. The mixed gas is then pumped into the tanker trucks for delivery to the stations.
Basically, high test is exactly the same as low test gas, with more additives and detergents; less cynically, low test is just high test gas with fewer additives.
At one time, there was only one gas that used to come in its own slug (slugs separate refinery products, e.g. automobile gas, aviation gas, diesel/heating fuel, keroscene, etc.) and that was Amoco "White Gas" or pure gas, which was their high test "straight gas" with minimum additives. Since the LBO by BP, it's called Ultimate. It's almost white (clear) in color; there is moderate evaporation loss in the new ventless cans; IMHO it's the cleanest burning and nicest starting gas I've used.
To my shock--nowadays (as opposed to 15 years ago) all gas is the supposedly the same, as to the gasoline part that is. The difference between brands (exxon, bp-amoco, etc.) and octanes, which differences are not insignificant, is in the "patented" additives, detergents, etc., of each "producer." The only things that the producers produce are their buckets of additives. The "slugs" of gas from various refineries arrive at the tank farms in the transcontinental pipelines, 30 to 36 inch, where the gas is then stored in the dealer tanks, where their "unique" additives are mixed. The mixed gas is then pumped into the tanker trucks for delivery to the stations.
Basically, high test is exactly the same as low test gas, with more additives and detergents; less cynically, low test is just high test gas with fewer additives.
At one time, there was only one gas that used to come in its own slug (slugs separate refinery products, e.g. automobile gas, aviation gas, diesel/heating fuel, keroscene, etc.) and that was Amoco "White Gas" or pure gas, which was their high test "straight gas" with minimum additives. Since the LBO by BP, it's called Ultimate. It's almost white (clear) in color; there is moderate evaporation loss in the new ventless cans; IMHO it's the cleanest burning and nicest starting gas I've used.
ksbeerhunter
New Member
high octane fuel
I have been using the lowest octane, regular grade, because where I live we have ethanol in everything else. Ate my diaphram out rather quickly. Any one recommend an additive that will both raise octane and spare the diaphram?
I have been using the lowest octane, regular grade, because where I live we have ethanol in everything else. Ate my diaphram out rather quickly. Any one recommend an additive that will both raise octane and spare the diaphram?
Al Smith
Addicted to ArboristSite
Unless things have changed,the statement that all gasoline is the same,grammatically is correct.
In the 80's when all the bulks stations went to bottom load ,vapor recovery type,they just hauled form different terminals while theirs was being converted.I worked on four of them,Sohio[standard oil of Ohio],Marathon,Shell and Gulf.
We just set temporary additive dispersement pumps and they mixed their own,as well as the dying agents for color.Undyed gas is like water.
In the case of Marathon which is also Gastown,Starvin Marvin and several others,it's the same additives,just less of them.
The gasoline,at the refinery,is tested with an apparatus appropriable called a knock engine,which measures the "knocks".They adjust their process based on the results of this test,along with several others.I might add that most modern auto engines also use a knock sensor to adjust the engine timing .
In the 80's when all the bulks stations went to bottom load ,vapor recovery type,they just hauled form different terminals while theirs was being converted.I worked on four of them,Sohio[standard oil of Ohio],Marathon,Shell and Gulf.
We just set temporary additive dispersement pumps and they mixed their own,as well as the dying agents for color.Undyed gas is like water.
In the case of Marathon which is also Gastown,Starvin Marvin and several others,it's the same additives,just less of them.
The gasoline,at the refinery,is tested with an apparatus appropriable called a knock engine,which measures the "knocks".They adjust their process based on the results of this test,along with several others.I might add that most modern auto engines also use a knock sensor to adjust the engine timing .
bvaught
ArboristSite Operative
ksbeerhunter said:
Tetra Ethyl Lead
actually the higher octane will decrease performance but it runs cooler. I saw use what your saw calls for and be happy. Higher octane decreases knocking. The only time i would run it is if my saw was modified. again it runs cooler, but doesn't increase performance. Just the opposite.
Semi, Re read this thread, Your post is totaly false.
